The present invention relates to a method and a device for crimping synthetic plastic fibers.
More particularly, this invention concerns a method and a device for the simultaneous crimping of a plurality of synthetic plastic fibers.
It is known in the art to entrain synthetic plastic fibers with a stream of hot gas to plasticize the fibers and then to admit such plasticized fibers into a crimping chamber, where the fibers are crimped.
It has been recognized that productivity of such a device is considerably limited by the holding capacity of the crimping chamber. It has also been noticed that the smaller the holding capacity of the crimping chamber, the more intensive the crimping action. But in the latter case only a limited number of fibers can be simultaneously crimped. One can increase the number of simultaneously crimped fibers by correspondingly increasing the holding capacity of the crimping chamber but this results in undesirably decreasing the crimping effectiveness of the device. Besides, it is then difficult to subsequently wind up the separated fibers in crimped condition.
In two known devices taught in U.S. Pat. No. 3,827,113 to Vidal et al and U.S. Pat. No. 3,895,420 to Strutz et al, attempts have been made to keep crimping quality high while crimping many fibers simultaneously. In both devices, the fibers are blown into a stuffing box after being crimped in the crimping chamber. The stuffed fibers are wadded together in the stuffing box and are withdrawn therefrom for subsequent winding on separate takeup spools.
These devices, while successfully achieving their original objectives, introduce new problems. Firstly, it is practically impossible, when the speed of operation is in excess of 1000 m/min, to properly insert the fibers into the device and to start the operation. Such insertion can be accomplished only when the feed spools are stopped. Secondly, the interior of the crimping chamber will always be filled with the fibers, so that each fiber has many points of contact with adjacent fibers, and the fibers may become entangled with one another.
Thirdly, the air outlets from the stuffing box must be carefully manufactured to avoid sharp edges. These edges can cause breaking and clogging of the fibers, and thereby interfere with smooth operation of the takeup spools.